Directional radio steering device



Feb. 7, 3933. E. A. SPERRY, JR, ET AL 3,395,8535

DIRECTIONAL RADIO STEERING DEVICE Original Filed Feb. 20, 1930 2Sheets-Sheet l Feb. 1933- E. A. SPERRY, .Jl-EZ, ET AL 6% DIRECTIONALRADIO STEERING DEVICE Original Filed Feb. 20, 1930 2 Sheets-Sheet 2 11vPZEN Toms 52mm? f7, SPA-m? y. Jfia :4 ATTORNEY.

raremeu reul, 1903 uairaa s'mras aaaaaaa FATENT QFFHE ELMER A. SPERRY,JR., OF BROOKLYN, NEW YORK, AND BRUNO A. WITTKUHNS, OF CHATHAM, NEWJERSEY, ASSIGNORS T SPERRY GYROSCOPE COMPANY, INC., OF BROOKLYN, NEWYORK, A CORPORATION OF NEW YORK of flying blind, that is, in fog orclouds, and

DIRECTIONAL RADIO STEERING DEVICE Application filed February 20, 1930,Serial No. 429,886. Renewed June 23, 1932.

This invention relates to automatic or semi-automatic steering means fordirigible craft, such as aircraft. The invention is especially designedto overcome the hazards the purpose is to maintain an aircraft flyingtoward the radio beacon or other transmitting stations regardless ofweather conditions or the skill of the pilot. For the above purpose weprefer to employ as a baseline a gyroscope, and to correct the coursefrom time to time automatically from a directional radio receiving meanson the craft. This may be done either through the gyroscope orindependently of the same.

Referring to the drawings in which several forms of the invention areshown Fig. 1 is a wiring diagram showing the elements of the invention,the gyroscope being shown in side elevation.

Fig. 2 is a diagram of a modified form of the invention in which agyroscope is not employed, at least when the craft is being steered fromthe radio beacon.

Fig. 3 shows a side elevation of a modified form of torque-applyingmeans for the gyroscope.

Fig. 4 is an end elevation of the gyroscope shown in Fig. 1, showingalso diagrammatically the servo motor operated therefrom with thefollow-up connections.

The usual practice in sending out radio beacons is to send out on asingle carrier wave two signals of different audio-frequencies which aretransmitted when the directional sending apparatus is at difi'erentangles so that in efiect two beams, at an angle to each other, are sentout. The present practice is to have some form of audible or visibleindicator on the aircraft which tells the operator which beam is thestronger and thereby tells him which way to turn to keep midway betweenthe beams by which he keeps his craft headed toward the transmittingstation. Our invention is shown designed to operate with such a form ofradio beacon although it is obvious that with slight modification theinvention could be adapted to work with other forms of radio beacons orsignals, such as where separate carrier waves are transmitted at anangle, or a direction finder on the craft is used with one or moresending stations.

In Fig. 1, 1 represents the antenna on the dirigible craft which picksup the radio signals represented by beams 7 and 8. Such signals may beamplified in an suitable form of radio detecting and amp ifying means,such as frequency amplifier 2, detector 3, and a broad bandaudio-frequency amplifier 4. Either incorporated in amplifier 4 orinductively coupled to the output of said amplifier are a pair ofaudio-frequency oscillators 5 and 6, one of which is tuned to resonancefor the audio-frequency of one of the signals 7, and the other to thefrequency of the other signal 8. The terminals 9 and 10 of theoscillator 5 are connected between two elements of the vacuum tube 11,say between the grid and the filament, a C battery 12 being placed inthis circuit to maintain the proper grid bias. Similarly the terminals 9and 10 of the oscillator 6 are connected through the C battery 12between the grid and filament of vacuum tube 11.

The plate of each tube, directly or indirectly, is connected throughwires 44 and respectively to separate windings l3 and 13 respectively ona device associated with the gyroscope 14 for the purpose of changingthe course in one direction or the other, dependingupon which winding 13or 13 is excited the stronger. By having the proper grid bias on thetubes, each tube will act as a detector tube to rectify the current andtransmit sufficient D. C. current to excite the winding 13 and 13 whichis in circuit of the oscillator receiving the stronger signals morestrongly than the other winding. As shown, said windings form theopposed field windings of an electric motor 15 or other torqueapplyingdevice which is mounted on the trunnion axis 16 of the gyroscope 14 (seeFig. 4), so as to exert a torque on the gyroscope about its horizontalaxisin one direction or the other, causing precession of the gyroscopeabout its vertical axis to change its position on the craft. Thegyroscope proper is shown as mounted with three degrees of freedom, thegyro casing 14: being pivoted on horidrawn when the zontal trunnions 16within the vertical ring 17, the vertical ring being mounted for turningabout a vertical axis 17 within the fixed frame 18.

The position of the gyroscope relative to the aircraft serves to controlthe rudder or other steering element. This may be efiected by means ofreversing contacts on thegyroscope. As shown, said contacts are In theform of a split contact ring 19 and having a pair of annular contactsegments 40, 41 jsee Fig. 2) secured to the vertical ring 17.

ooperatin therewith is va trolley or brush 20 mounte at the base of thegyroscope. Preferably, instead of having the contact fixed, we provide-a follow-up connection thereto from the rudder or servo motor so thatthe rudder is only moved in proportion to the deviation. Said follow-upmay be introduced by mounting the trolley 20 on a pulley or drum 21,which is turned by means of the follow-up wires or cables 22 and 23leadin to the servo motor drum 24 (see also Fig. 4

The contacts on the gyroscope may control any form of servo motor, themotor shown being an electric motor 25 having opposed field windings26-26 WhlCh are excited from the aforesald contacts. The drum 24 isshown as directly connected to the rudder bar 27 which carries therudder 28. The gyroscope is also shown as equlpped wlth a lock or cage29. Th1s is normally withro is operated as by a spring (not shown butmay be brought into operation at the will of the aviator by pressing key30 which excites electro-magnet 31, thus pushing the lock to the rlghtin Flg. 1 through the bell crank lever 32. The lock is shown in the formof a bell mouthed member engaging a pin 32 projecting axially from thegyro casmg. It will be understood that the apparatus is so arran ed thatthe motor 15 will apply a torque on t e gyroscope in such a direction asto cause the gyroscope to turn toward the weaker beam and thereby turnthe plane toward the weaker beam until the beams become of equalstrength so that the aircraft is kept headedin such a direction as tomaintain the intensity of the two beams substantially equal or inpredetermined ratio.

If, however, the plane passes over the sending station and it is desiredto continue the flight in the same direction, it is necessary that therelation between the torque motor and beam intensities be reversed. Themeans we have shown for effecting this comprises a visual indicator,such as a lamp 34 in the common return from the motor 15 and the Bbattery 35. The moment the station is passed over no signal is receivedand hence the lamp will be momentarily extinguished or greatly dimmed,thereby notifying the aviator that he has passed over the station.

it that time the'aviator throws the reversmg sw1tch 36, thus revers ngthe direction of the torques applied to the gyroscope and enabllng himto contmueon his course. If he does not desire to continue but desiresto land near the sending station, the switch should not be thrown andthe-plane will start circling around the sending station. We havealsoshown a visual mdlcator 36, 37, in c1rcu1t with each motor field so'thatthe aviator may have a vlsual indication of the relative intensity 0?the radio beams as well, so that no other dlrectlon finder is needed. Itw1ll be understood that the wiring in Fig. 1 1s dlagrammatlc only, andno attempt has been made to show all of the condensers, choke co1ls,etc., deslginng such a circuit, or to relative size of such elements.

In Fig. 3 a sllghtly diiferent form of torque-applymg dev ce is shown.In this case a pan of solenoids 40-41 are fixed on opposite sides of thevertical ring and each act on magnetic cores 4243 secured to the gyrotrunn on. Said solenoids may be connected 1n c1rcu1t in the same manneras the fields 1313 and will exert opposed torques on the gyroscope aswill be readily understood. No cage is shown in this figure becauselocking means is unnecessary for the automatlc operatlon of the form ofdevice in Flgs. 1,3 and 4.

In F g. 2 is represented a different form of the inventlon which may beused either entlrelywithout a gyroscope or in conjunct1on w th agyroscope. In this form of the nvention the output of the tubes 11 and11 1s led through the wires 4445 directly .to a relay 46 and thereversing contacts 4849 on the relay operate the servo motor 25. Theradio beacon, therefore, in this form of the invention could steer theplane alone. However, we prefer to employ it in conjunction with a cagedgyroscope, such as shown in Fig. 1, as follows: Normally the gyroscopewould control the steering of the plane as in Fig. 1. Under theseconditions the switch 50 is on contact 51 and the gyroscope is helduncaged by solenoid 31' against the action of compression spring 52.When, however, the lamps 36 and 37 or other radio beam indicators showthe pilot that he is getting ofli his beacon course, the pilot throwsswitch 50 onto contact 53 which does two things first, it cages thegyroscope and'renders the gyro control inoperative by breaking thecircuit to the solenoid 31 and contacts 19-20, and second, it throws theservo motor 25 onto the relay 46. The pilot leaves the radio beacon incontrol until the lamps show that he is again on the beacon course whenthe throws switch 50 back, which causes the gyroscope to be released andto again assume control on the new course. By using a gyroscope to steernormally, the hunting or zigzagging indicate the which would be used inof the plane, which would take place if the gether with the apparatuswhich we now consider to represent the best embodiment thereof, but wedesire to have it understood that the apparatus shown is onlyillustrative and that the invention can be carried out by other means.Also, while it is designed to use the various features and elements inthe combination and relations described, some of these may be alteredand others omitted without interfering with the more general resultsoutlined, and the invention extends to such use.

Having described our invention, what we claim and desire to secure byLetters Pat ent is:

1. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, means for applying atorque about the horizontal axis of the gyroscope in either direction,and radio responsive means for controlling said torque means.

' 2. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, radio receivingmeans selectively responsive to the frequencies of a plurality of radiobeams, and differential means actuated thereby for turning the crafttoward the beam having the lesser intensity.

3. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steer ing the craft, radio receivingmeans selectively responsive to the frequencies of a plurality of radiobeams, differential meansactu ated thereby for applying a torque aboutthe horizontal axis of the gyroscope such as to cause precession of thegyroscope in a direction to maintain the craft midway between the beams.

4. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, radio receivingmeans selectively responsive to the frequencies of a plurality of radiobeams, differential means actuated thereby for turning the craft in apredetermined direction With respect to the stronger beam, and means forreversing the direction of turn when the beam transmitting station ispassed over.

5. Means for automatically steering an aircraft from radio beaconshaving different frequencies including the combination with the rudderand a radio receiver on the aircraft, of a plurality of oscillatorstherein respectively tuned to the frequencies transmitted by thebeacons, and reversible power means actuated from said oscillators forturning the rudder'to turn the craft toward the weaker beam.

6. Means forautomatically steering an aircraft from radio beacons havingdifferent frequencies including the combination with the rudder, asteering gyroscope, and a radio receiver on the aircraft, of a pluralityof oscillators therein respectively tuned to the frequencies transmittedby the beacons, and reversible power means actuated from said amplifyingmeans for applying torques on the gyroscope and thereby cause the craftto turn toward the weaker beam.

7. An automatic steering device for dirigible craft comprising agyroscope having freedom about a. vertical and a horizontal axis, meansactuated therefrom for normally steeringthe craft, and electrical meansforv applying a torque about the horizontal axis of the gyroscope ineither direction in response to the relative strength of a pair ofdirectional radio beams.

8. An automatic steering device for dirigible craft comprising a gyroscoe having freedom about a vertical and a horizontal axis, means actuatedtherefrom for normal ly steering the craft, radio receivingmeansselectively responsive to the frequencies of a plurality of radiobeams, differential means actuated thereby for turning the craft towardthe beam havingthe lesser intensity, and means for locking the gyroscopeand rendering the control therefrom inoperative while the course isbeing changed.

9. Means for automatically steering an aircraft from radio beaconshaving different frequencies including the combination with the rudderand a radio receiver on the aircraft, of a plurality of oscillatorstherein respectively tuned to the frequencies transmitted by thebeacons, reversible power means actuated from said oscillators, and agyroscope for normally maintaining the course, said power means beingconnected to the gyroscope so as to change the course to Iloiring thecraft midway between the radio earns.

10. Means forautomatically steering an shifting the control of saidpower means from said gyroscope to said oscillators when the craftstrays from the radio course.

11. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, electricallycontrolled means for applying a torque about the horizontal axis of thegyroscope in either direction, and radio means for bringing said torqueinto operation.

12. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, electricallycontrolled means for applying a torque about the horizontal axis of thegyroscope in either direction, and radio means for bringing said torqueinto operation in either direction to cause a change of course bycausing slow precession of said gyroscope about its vertical axis.

13. In a system for guiding aircraft toward a radio transmittingstation, the combination with the rudder of the craft and a servomotorfor turning the same, a gyroscope for controlling said servo motor to 4maintain the craft on any predetermined course, and directional radioresponsive means on the craft for correcting the course maintained bythe gyro to direct the course toward the transmitting station.

14. In a system for guiding aircraft to- Ward a radio transmittingstation, a directional gyroscope by which a course may be set andmaintained, directional radio responsive means on the craft responsiveto the relative direction of a, transmitting station, and meanscontrolled by said radio means for correcting or altering the courseindicated by the gyroscope.

15. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, means for'applying atorque about the horizontal axisof the gyroscope in either direction,directional radio responsive means on the craft responsive to therelative direction of a transmitting station, and means controlled bysaid radio means for bringing said torque. in action to correct theposition of the gyroscope.

16. An automatic steering device for dirigible craft comprising agyroscope having freedom about a vertical and a horizontal axis, meansactuated therefrom for normally steering the craft, directional radioreceiving means on the craft, means actuated there from for turning thecraft toward the sending station, and means for locking the gyroscopeand rendering the control therefrom inoperative changed.

In testimon signatures.

ELMER A. SPERRY, JR.

BRUNO A. WI

TTKUHNS.

y whereof .we have afiixed our

